Closure for food container

ABSTRACT

A closure for a preformed food container such as an sandwich wedge comprises a one-piece blank including an aperture ( 4 ) into which the food container is inserted. The blank is foldable about a predetermined line ( 6 ) to form a front wall ( 8 ) overlying a back wall ( 9 ) and trapping between the front and back walls a projecting lip extending from a rim of the container. The front ( 8 ) and back ( 9 ) walls are sealed together, thereby closing the container.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application claims priority from Provisional Application U.S.Application 61/723,112, filed Nov. 6, 2012, incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

The present invention relates to a closure system which is used for theheat seal or self-seal of pre-formed plastics-based or cardboard-basedcontainers for use with food products.

BACKGROUND OF THE INVENTION

Plastic and cardboard sandwich wedges and other food containers havebeen around for many years. The plastics-based containers are usuallysealed with a film, whereas the cardboard-based products are sealed bymelting a PE (polyethylene) coating to form a seal.

SUMMARY OF THE INVENTION

We provide a method of sealing a food container such as an “opensandwich wedge” by the use of a cut and creased and folded piece ofboard with an applied film window.

The “Open sandwich wedge board closure” is coated by either apolypropylene- or glue-based laminate on one side which, either via heatand pressure or just pressure, seals to itself.

The open wedge (open wedge material can be paper, board or an oil-basedderivative) is inserted into an aperture in the Open sandwich wedgeboard closure. The Open sandwich wedge board closure is then folded inhalf allowing the two inner sides of the Open sandwich wedge boardclosure to meet.

When pressure (with glue only) or heat and pressure (with apolypropylene or similar laminate) are applied, adhesion occurs whichseals the two inner sides of the Open sandwich wedge board closuretogether, thus securing and sealing the open wedge to the Open sandwichwedge board closure and ensuring the product packed stays fresh andsecuring the product for counter display.

A window made from a clear film on the opposite side to the apertureallows the product to be seen for display purposes.

According to a first aspect of the present invention we provide aclosure for a preformed food container comprising:

(a) a one-piece blank foldable about a predetermined line to form afront wall overlying a back wall and trapping a portion of the containerbetween the front and back walls; and

(b) a seal between the front and back walls of the blank.

Preferably but without limitation, the container includes an open cavityto receive at least one food item and a projecting lip extending from arim of the cavity; the closure includes an aperture in the back walladapted to receive the food container with the lip overlying the backwall; and in use the lip of the food container is trapped between thefront and back walls of the blank.

Preferably, in use the contents of the food container are visiblethrough the front wall of the blank, for example by incorporating atransparent window in the front wall of the blank.

According to another aspect of the present invention we provide a methodof closing a preformed food container by means of a one-piece blankfoldable about a predetermined line to form a front wall overlying aback wall, wherein the container includes an open cavity to receive atleast one food item and a projecting lip extending from a rim of thecavity, and the method includes the steps of:

(a) inserting the food container through an aperture in the back wall ofthe blank so that the lip overlies the back wall;

(b) folding the front wall of the blank over the back wall so as to trapthe lip of the food container between the front and back walls of theblank; and

(c) sealing together the front and back walls of the blank.

The seal may be formed by application of heat or pressure or anycombination of heat and pressure.

Preferably, the seal is tamper-proof, that is the closed containercannot be opened without leaving visible evidence of access. The sealmay be demountable, in which case it should not be resealable, or a usermay gain access to the contents of the container by cutting or tearingthe container or closure, for example by means of a tear strip.

Preferably, at least a significant proportion of the closure is made ofbiodegradable material such as cardboard.

It will be appreciated that the terms “front wall” and “back wall” donot necessitate any particular orientation but are convenient labels todistinguish between the two layers of the blank after they are foldedone over the other.

Accordingly, in the first aspect of the present invention, the blank isproduced from one piece of cardboard wherein the closure comprises:

an aperture in the “back wall” that fits around and under a container'sbody and lip;

a window which is formed by the application of a transparent filmclosing an aperture on the opposite panel (the “front wall”)

an application of self-adhesive glue or a polyethylene (PE) coating; and

a crease along the centre of the blank allowing the folding of thepresent invention to secure the container and seal the open cavitythereof.

In a preferred embodiment, the back wall of the blank will include anaperture that would be suitable for all sizes and shapes of containers.

In a preferred embodiment, the front wall of the blank would have anaperture which would be covered with a clear plastic material to allowthe contents of the food item to be viewed.

As indicated above, the one piece blank is cut and folded, with twocut-outs, one to hold a container and the other to have clear filmplastic applied to form a window. A PE coating laminated to thecardboard will seal the front and back walls together using heat andpressure. An alternative to the PE coating is an applied adhesive whichon contact with adhesive on an opposite surface forms a seal without theuse of heat, only pressure.

This invention enables the closure of a preformed food container. Byfolding the blank in half the opposed faces of the blank touch and so aseal can be formed, trapping the lip of the container between the twopieces of cardboard and closing the container.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention will be further described withreference to the following drawings in which:

FIG. 1 shows a plan of a blank according to the present invention;

FIG. 2 shows an elevation of the sealing mechanism in the closedposition from the rear;

FIG. 3 shows an elevation of the sealing mechanism in the closedposition from the front;

FIG. 4 shows an elevation of the sealing mechanism with arrow 10 showingthe insertion direction of the food container and arrow 11 showing thefolding of the blank.

DESCRIPTION OF THE PREFERRED EMBODIMENT

As FIG. 1 shows, the closure blank is formed from a single piece ofcardboard. The blank consists of a front wall 8, which is rectangular inshape. One of the long edges of the front wall connects to a back wall9, also rectangular in shape, via a crease 6; this could be also aperforation or score.

In the back wall, an aperture 4 allows the insertion of the container(not shown) to be sealed. This aperture will be produced to the correctsize to fit the container's dimensions.

In the front wall 8, there is an aperture 5, which allows theapplication of a clear plastic film window 7 to allow the contents ofthe container to be viewed.

As FIG. 2 shows, the blank is folded and sealed. The aperture 4, whichwould hold the container, is clear to see and the aperture 5, which hasa plastic clear film to form a window 7, on the opposite panel can beseen. The lip of the container would be now sandwiched between frontwall 8 and back wall 9.

As FIG. 3 shows, the blank is folded and sealed, the aperture 5, withthe clear plastic film window 7, is visible; the lip of the containerplaced into the aperture would now be sandwiched between the front wall8 and the back wall (not visible under front wall 8).

As FIG. 4 shows, the arrow 10 shows the direction of placement of thecontainer to be sealed; arrow 11 shows the folding of the blank whichwould then sandwich the container into place, thereby trapping the lipof the container between front wall 8 and back wall 9.

What is claimed is:
 1. A closure for a preformed food containercomprising: a one-piece blank configured to fold about a predeterminedline to form a front wall overlying a back wall and to trap a portion ofthe container between the front and back walls; and a seal disposedbetween the front and back walls of the blank.
 2. A closure for apreformed food container having an open cavity configured to receive atleast one food item and a projecting lip extending from a rim of thecavity, the closure comprising: a one-piece blank configured to foldabout a predetermined line to form a front wall overlying a back wall;and a seal disposed between the front and back walls of the blank,wherein the back wall comprises an aperture configured to receive thefood container with the lip overlying the back wall such that, in use,the lip of the food container is trapped between the front and backwalls of the blank.
 3. The closure as claimed in claim 2, wherein, inuse, contents of the food container are visible through the front wallof the blank.
 4. The closure as claimed in claim 2, wherein the frontwall comprises a transparent window.
 5. The closure as claimed in claim2, wherein the seal is formed by application of heat.
 6. The closure asclaimed in claim 2, wherein the seal is formed by application ofpressure.
 7. The closure as claimed in claim 2, wherein the seal isdemountable.
 8. The closure as claimed in claim 2, wherein the seal istamper-proof.
 9. The closure as claimed in claim 2, wherein the closureis substantially made of a biodegradable material.
 10. The closure asclaimed in claim 9, wherein the biodegradable material is cardboard. 11.A one-piece blank configured to form a closure for a preformed foodcontainer comprising: a portion foldable about a predetermined line toform a front wall overlying a back wall and to trap a portion of thecontainer between the front and back walls; and a seal disposed betweenthe front and back walls of the blank.
 12. A one-piece blank adapted toform a closure for a preformed food container having an open cavityconfigured to receive at least one food item and a projecting lipextending from a rim of the cavity, the blank comprising: a portionfoldable about a predetermined line to form a front wall overlying aback wall; and a seal disposed between the front and back walls of theblank, wherein the back wall comprises an aperture configured to receivethe food container with the lip overlying the back wall such that, inuse, the lip of the food container is trapped between the front and backwalls of the blank.
 13. A method of closing a preformed food containervia a one-piece blank configured to fold about a predetermined line toform a front wall overlying a back wall, wherein the food containerincludes an open cavity configured to receive at least one food item anda projecting lip extending from a rim of the cavity, the methodcomprising the steps of: inserting the food container through anaperture in the back wall of the blank such that the lip overlies theback wall; folding the front wall of the blank over the back wall totrap the lip of the food container between the front and back walls ofthe blank; and sealing together the front and back walls of the blank.14. The method as claimed in claim 13, wherein the sealing comprisesforming a seal by application of heat, pressure, or a combinationthereof.